How are earthquakes recorded? (Station)
How are earthquakes recorded? (Station) Part of the Exploring Earth Using Seismology poster. An important tool to study the Earth’s interior is the seismograph. The seismograph is an instrument that records ground motion, or seismic waves, generated by earthquakes. Seismographs can be installed permanently or temporarily. Temporary installments are used to answer scientific questions of geological interest such as here near the base of the Nangar Parbat massif in northeast Pakistan.
Permanent installments are used to study the overall structure of the Earth’s interior. Seismographs used in permanent installments are deployed at fixed locations around the world. Modern seismographs record and amplify seismic waves electronically, and can detect ground motion as small as 0.00000001 cm (distances of the order of atomic spacing.)
The principle by which a seismometer works can be thought of as a heavy mass freely attached to a frame fixed to the Earth. When seismic waves reach the seismometer, the frame moves along with the ground. The heavy mass inside the frame remains stationary because of its inertia. The relative motion between the frame and the mass is a measure the of ground motion.